The present invention pertains to an apparatus for holding a horizontal sliding gate against the frame defining the discharge opening of a railroad hopper car. When a hopper car is holding a fluidized lading such as fine particles of bauxite, bentonite, cement, flour, etc., problems are encountered with respect to that fluidized lading sifting between the gate and the frame even though the gate presumably is in the closed position. One solution has been to use gaskets of rubber or the like. If the gasket is to provide an effective seal it must be pressed securely against the gate, but this can interfere with the horizontal movement of the gate and/or result in excessive wear of the gasket. Thus various devices have been devised which will give the gate, in addition to its normal horizontal movement of opening and closing, a vertical movement when it is in the horizontal position below the opening. Thus such vertical movement acts to move the closed gate away from the gasket or the discharge opening so that the normal horizontal movement then can take place with less interference. Conversely, as the gate is moved to the closed position the final part of the movement includes at least a component which is vertical.
One device for such a vertical movement employs some blocks on the underside of the gate which move onto rollers as the gate approaches the closed position thereby raising the gate against the part of the frame defining the discharge opening (e.g., U.S. Pat. No. 3,845,726, issued Nov. 5, 1974). Such an apparatus has the problem that the gate is raised even before it reaches its final closed position, the result being that there still is horizontal movement after the gate has been raised. That is, while this solution reduces the portion of the opening movement during which the gate is raised, it does not eliminate it altogether. Another device employs fluid or mechanical pressure to lower and raise the gate before and after the horizontal movement of the gate takes place. Examples thereof are seen in U.S. Pat. No. 3,224,382, issued Dec. 21, 1965. In the mechanical pressure version, shafts along each side of the gate and parallel to the path of horizontal movement of the gate are rotated and as this is done protrusions on the shafts cam the shafts and gate upwardly. Such devices, however, add significantly to the apparatus required and thus to the overall cost, etc. Furthermore, they often necessitate two separate operations to move a gate to and away from the closed position, i.e., an operation to achieve the vertical movement as well as the normal operation to achieve the horizontal movement.
As compared to some such prior art devices, the present invention provides a vertical component of movement as a part of finally locating the gate in the closed position and in its initial movement away from the closed position. Thus the drag occasioned by the horizontal gate movement commences to be relieved almost immediately in the part of the gate movement away from the closed position and recommences only at the very final stage of the gate movement to the closed position. As compared to other prior art devices, the parts that must be added to the conventional gate structure in creating an embodiment of the invention are very nominal. Thus the added cost is relatively limited. Embodiments of the invention do not require a second operation or manipulation. The normal horizontal actuation of the gate supplies the power to achieve the vertical movement. The invention employs pivoted lever arms which engage abutments on the bottom of the gate as the gate is moving in its final part of the horizontal movement toward the closed position with the levers pivoting to an upright position thereby lifting the gate against the bottom of the frame structure and gaskets, if any, surrounding the discharge opening.
Further objects and advantages will become apparent from the following description taken in conjunction with the drawings.